Navegação Ciências Exatas e da Terra por Data do documento
Resultados 1-20 de 6355
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Investigation of medium and heavy nuclei by quasi-free-proton scattering
(1960) [Artigo de periódico] -
Quantum electrodynamics with zero bare ferminon mass
(1964) [Artigo de periódico] -
Spontaneously broken symmetries and current conservation
(1966) [Artigo de periódico] -
Studies of quadrupole interactions by means of angular correlations
(1967) [Artigo de periódico]Measurements of the nuclear quadrupole interaction have been made for the first 5/2+ excited state of Ta181 in severa! compounds of Hf, and for the first 5/2+ excited state of Cdll1 in In metal by time-differential and by ... -
Evidence for sinusoidal phase modulation in small self-trapped filaments
(1968) [Artigo de periódico]Evidence is presented indicating that, in some cases at least, a sinusoidal phase modulation is responsible for the spectral broadening Observed in trapped filaments of laser (and Raman) light. This kind of modulation has ... -
Charge commutator for any momentum
(1969) [Artigo de periódico]The nucleon matrix elements of the charge commutation relations are considered for arbitrary momentum. The resulting expression is exact. The high-momentum limit reduces to the Alder-Weisberger sum rule. For zero momentum ... -
Mossbauer effect in frozen solutions of nitroprusside
(1969) [Artigo de periódico] -
Interpretation of nuclear quadrupole constants in compounds of 181Ta
(1969) [Artigo de periódico] -
Measurement of the g-factor of the 3/sup -/ octopole vibrational state in /sup 208/pb
(1969) [Artigo de periódico]The nuclear g-factor of the collective 3- level at 2615 keV in 208pb has been measured by the perturbed angular correlation technique. The result of g(3-) = 0.58 ± 0.14 confirms the strongly collective character of the state. -
Internal magnetic fields at Hg and TI in ferromagnets
(1969) [Artigo de periódico]With the perturbed angular correlation method the hyperfine magnetic fields acting at 198Hg nuclei embedded in Fe, Co and Ni lattices are found to be -440 J: 105 kG, -370 :~ 78 kG and -86 J: 22 kG, respectively. The measured ... -
Influence of simultaneous static and time dependent quadrupole interactions on gamma-gamma angular correlations
(1969) [Artigo de periódico]We derive the forro of the perturbation factors for the angular correlation of two successive Y rays when the intermediate state is under the influence of an axially symmetric static electric field gradient plus a small ... -
Renormalization and gauge invariance in quantum electrodynamics
(1970) [Artigo de periódico]The connection between the field theory and the perturbation expansion of quantum electrodynamics is studied. As a starting point the usual Lagrangian is taken but with bare electron mass and the renormalization constant ... -
Isomer shift and electronegativy in compounds of tin and group -VI elements
(1970) [Artigo de periódico]Using the Mössbauer effect in 119Sn we have measured the isomer shift in compounds of divalent and tetravalent tin with elements of Group VI. The isomer shift is linearly dependent on the values of electronegativity in ... -
Rare-earth tri-iodides-mossbauer effect using /sup 129/i
(1970) [Artigo de periódico] -
g factor of the 50-kev/sub 3/2/-state in /sup 223/ra and the internal magnetic fields at ra nuclei in ferromagnets
(1970) [Artigo de periódico]The y-y perturbed angular correlation of the 236-50-keV cascade in 223Ra has been investigated, yielding g(3/2-, 50 keV) =+0.28 ±0.04. The magnetic hyperfine fields experienced by Ra nuclei embedded in Ni, Co, and Fe ... -
Nuclear relaxation in (nh/sub 4/)/sub 3/hff/sub 7/ studied by gamma-gamma angular correlation
(1970) [Artigo de periódico]Measurements of the perturbed angular correlation have been made for the first 5/2+ excited statc of Ta181 in (NH4) 3HfF7 in arder to solve a controversial question related to the structure of the complex Hf7 this compound. ... -
Exact photocount distributions for laser near threshold
(1970) [Artigo de periódico]Photocount fluctuation problems, treated previously for Gaussian statistics only, or in the limit of short measurement times, have been extended to arbitrary times (compared with the intensity correlation time) and to ... -
Influence of combined static and time-dependent quadrupole interactions on angular correlation in nuclei with integral spin
(1971) [Artigo de periódico]The application of the Bloch-Wangsness-Redfield theory of nuclear relaxation to the study of perturbed angular correlations in even-A nuclei subject to simultaneous static and timedependent quadrupole interactions bas been ... -
Maps of the distribution of atomic hydrogen in a region in centaurus
(1971) [Artigo de periódico]We have made a survey of the region 302° ≤ l ≤ 310°, 2° ≤ b ≤ 12° at the frequency of the hydrogen line. We have detected three elongated features that run parallel to the galactic plane at heights of about 200 pc above ... -
Simple theory of the magnetic properties of rare-earth metals
(1971) [Artigo de periódico]A simple theory for the magnetism of the rare-earth metals is presented. It is based on assuming strongly correlated, well-defined f-electron states of an atomiclike character which are weakly hybridized with conduction-band ...
